The present invention relates to a novel organopolysiloxane-modified polyester in which there is grafted both silicon-bonded hydrolyzable group-free organopolysiloxanes and silicon-bonded hydrolyzable group-containing silicon compounds. The invention also relates to a method for the preparation of the novel organopolysiloxane-modified polyesters.
The modification of polyesters with organopolysiloxanes has long been known. This tactic is effective for improving such properties as water repellency, weather resistance, and slip. Among organopolysiloxane-modified polyesters, interest has most recently focused in particular on organopolysiloxane-grafted polyesters such as those disclosed in Japanese Patent Application Laid Open [Kokai or Unexamined] No. 3-74459 [74,459/1991]. Other organopolysiloxane-grafted polyesters have also been disclosed such as those described in Japanese Patent Application Laid Open No. 3-2221 [2,221/1991]. This organopolysiloxane-grafted polyester resin was disclosed as being useful as a modifier for various types of organic resins, for example, polyester resins, and polyurethane resins.
However, the organopolysiloxane-grafted polyester resins described above are noncrosslinking. As a result, when they are used, for example, as coatings, the resulting film is fragile and redissolves when brought into contact with a solvent. The development is therefore desired of an organopolysiloxane-grafted polyester resin that is capable of crosslinking at room temperature.